CWE-655 Class Draft

Insufficient Psychological Acceptability

This weakness occurs when security features are so cumbersome or confusing that well-intentioned users feel forced to turn them off or find workarounds, defeating their purpose entirely.

Definition

What is CWE-655?

This weakness occurs when security features are so cumbersome or confusing that well-intentioned users feel forced to turn them off or find workarounds, defeating their purpose entirely.
At its core, this is a design failure that prioritizes theoretical security over real-world usability. When features like complex password rules, frequent re-authentication prompts, or convoluted privacy settings create significant friction, users will naturally seek the path of least resistance. This often means disabling the protection altogether, using weak passwords to meet requirements, or sharing credentials to avoid login hassles—actions that introduce far greater risk than the feature was meant to prevent. To avoid this, security must be baked into the user experience, not bolted on as an obstacle. Developers should design controls that are intuitive, context-aware, and minimally invasive. For example, offering biometric authentication alongside passwords, using risk-based authentication to reduce unnecessary prompts, or providing clear, immediate value for security actions. The goal is to make the secure choice the easiest and most obvious one, aligning security objectives with natural user behavior rather than fighting against it.
Real-world impact

Real-world CVEs caused by CWE-655

No public CVE references are linked to this CWE in MITRE's catalog yet.

How attackers exploit it

Step-by-step attacker path

  1. 1

    In "Usability of Security: A Case Study" [REF-540], the authors consider human factors in a cryptography product. Some of the weakness relevant discoveries of this case study were: users accidentally leaked sensitive information, could not figure out how to perform some tasks, thought they were enabling a security option when they were not, and made improper trust decisions.

  2. 2

    Enforcing complex and difficult-to-remember passwords that need to be frequently changed for access to trivial resources, e.g., to use a black-and-white printer. Complex password requirements can also cause users to store the passwords in an unsafe manner so they don't have to remember them, such as using a sticky note or saving them in an unencrypted file.

  3. 3

    Some CAPTCHA utilities produce images that are too difficult for a human to read, causing user frustration.

Vulnerable code example

Vulnerable pseudo

MITRE has not published a code example for this CWE. The pattern below is illustrative — see Resources for canonical references.

Vulnerable pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
Secure code example

Secure pseudo

Secure pseudo 
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist

How to prevent CWE-655

  • Testing Where possible, perform human factors and usability studies to identify where your product's security mechanisms are difficult to use, and why.
  • Architecture and Design Make the security mechanism as seamless as possible, while also providing the user with sufficient details when a security decision produces unexpected results.
Detection signals

How to detect CWE-655

SAST High

Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.

DAST Moderate

Run dynamic application security testing against the live endpoint.

Runtime Moderate

Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.

Code review Moderate

Code review: flag any new code that handles input from this surface without using the validated framework helpers.

Plexicus auto-fix

Plexicus auto-detects CWE-655 and opens a fix PR in under 60 seconds.

Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.

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Frequently asked questions

Frequently asked questions

What is CWE-655?

This weakness occurs when security features are so cumbersome or confusing that well-intentioned users feel forced to turn them off or find workarounds, defeating their purpose entirely.

How serious is CWE-655?

MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.

What languages or platforms are affected by CWE-655?

MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.

How can I prevent CWE-655?

Where possible, perform human factors and usability studies to identify where your product's security mechanisms are difficult to use, and why. Make the security mechanism as seamless as possible, while also providing the user with sufficient details when a security decision produces unexpected results.

How does Plexicus detect and fix CWE-655?

Plexicus's SAST engine matches the data-flow signature for CWE-655 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.

Where can I learn more about CWE-655?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/655.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-655

CWE-657 Parent

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CWE-636 Sibling

Not Failing Securely ('Failing Open')

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CWE-637 Sibling

Unnecessary Complexity in Protection Mechanism (Not Using 'Economy of Mechanism')

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CWE-638 Sibling

Not Using Complete Mediation

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CWE-653 Sibling

Improper Isolation or Compartmentalization

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CWE-654 Sibling

Reliance on a Single Factor in a Security Decision

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Resources

Further reading

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